Laser was just used about 40 years ago. Since then, the laser industry has progressed greatly. Numerous kinds of laser have been developed in succession, for example, ruby laser (1960) followed by glass laser (1961), He—Ne laser (1962), semiconductor laser (1962), CO2 laser (1964), X-ray laser (1972), excimer laser (1975), and free electron laser (1977). In addition, laser are very important and widely applied in communications, measurement, processing, medical treatment and so on.
Lasers with various structures and power are applied in various fields. For example, lasers used in household optical fiber communication are significantly different from those used in industrial cutting. Moreover, according to the applied properties, laser can be divided into pulse laser, continuously oscillating laser and the like. Of these, the majority of laser-emitting devices must be driven by high power.
In order to drive such a high power laser to achieve the required application, the laser-emitting device usually needs to be provided with a higher driving current, such as 10 amperes or more. However, the driver circuit designed for high current is complicated in its structure as well as expensive in cost. Hence, the high power laser-emitting device can be driven by a sufficiently high current collected by parallel connecting multiple driving currents in the prior art.
Reference is made to FIG. 1, which is a pulse-modulation laser system composed in accordance with the aforementioned method. The system has a high power laser-emitting device 10, a feedback circuit 12, a pulse-generating circuit 14, and N sets of driver circuits 161, 162, . . . , and 16N. The pulse-generating circuit 14 is employed to generate a pulse controlling signal to the driver circuits 161, 162, . . . , and 16N. The driver circuits 161, 162, . . . , and 16N respectively generate driving currents, and the driving currents are collected for driving the high power laser-emitting device 10. For example, a driving current of 10 amperes can be obtained by collecting the output of 100 driver circuits, where each driver circuit generates 0.1 amperes. Further, in order to keep the emitting power of the high power laser-emitting device 10 stable, the feedback circuit 12 is responsible for monitoring the power of the high power laser-emitting device 10, and provides a feedback signal to the driver circuits 161, 162, . . . , and 16N.
Since the prior art merely adopts a single feedback circuit 12, and all driver circuits 161, 162, . . . , and 16N are connected to the feedback circuit 12, if a driver circuit is broken, other driver circuits may be burned to induce a chain reaction. In addition, the prior method is not stable enough, as well as being very difficult to be repaired.